So I’m currently rereading The Exorcist…and it’s truly amazing how every single time you will notice something new. During the scene where Karras and Chris are discussing letters appearing on Regan’s skin, it would appear that he mentions the Gemini killer.
“Karras shook his head. “Look, I’ve come across cases of that in the journals and the Bishop could bring it up against us. There was one, I remember, where a prison psychiatrist reported that a patient of his—an inmate—could go into a self-induced state of trance and make the signs of the zodiac appear on his skin.” He made a gesture at his chest. “Made the skin raise up.”
I wonder how much of Legion Blatty was already writing in his head when he was working on The Exorcist?